The present invention generally relates to electronic interconnect devices used to provide a communications path between electronic devices. More particularly, this invention relates to a high-density cable comprised of flexible circuits with integral terminations, and a method for manufacturing the cable.
Medical ultrasound procedures employ an ultrasonic probe with piezoelectric transducer elements connected to multiplexing circuitry that is remotely located from the element and processes the ultrasound signals from the probe. Due to the quantity of signals generated, high-density cables are necessary to faithfully transmit the ultrasound signals to the multiplexing circuitry.
Multiconductor coaxial cables have been used to connect ultrasound equipment as well as numerous other electronic devices. These cables contain as many as five hundred to six hundred very small (e.g., less than 0.015 inch (about 0.4 mm)) coaxial conductors in a round sheath. Each coaxial conductor contains a center conductor of very small diameter wire that is fragile and therefore difficult to work with. Due to the fragility of the center conductors, each end of the cable must be connected to a fanout board to enable the cable to be reliably connected to the probe and multiplexing circuitry. During the process of terminating the cable, each individual coaxial conductor must be identified and connected to the proper fanout board terminal. This process is time-consuming and difficult to automate due to the size and fragility of the conductors, which drives up the cost of these cables. Another shortcoming is that a cable containing five hundred or more coaxial conductors is relatively large and stiff, which renders the cable rather difficult to use for diagnostics in a clinical environment.
From the above, it can be seen that it would be desirable if a relatively flexible and pliable high-density cable were available that did not require an assembly and termination process as intensive as conventional coaxial cables.
The present invention provides a high-density cable that is suitable, for example, for transmitting ultrasound signals from an ultrasonic probe to an output connector and/or multiplexing circuitry during a medical ultrasound procedure. The output connector may or may not include multiplexing circuitry and/or tuning inductors, for example. The cable is less complicated to fabricate and terminate than conventional multiconductor cables that include individual coaxial conductors, thereby reducing the cost of the cable without any loss in transmission capability.
The cable of this invention includes one or more (at least one) flexible circuits that are arranged within a flexible sheath that surrounds and confines the flexible circuits. Each flexible circuit includes an elongate flexible substrate with oppositely-disposed surfaces and multiple conductors on at least one of these surfaces. The opposing longitudinal ends of the substrate define integral connection regions for (a) connecting with a mating connector of an electronic device, such as an ultrasonic probe or multiplexing circuitry and/or (b) connecting the cable with a mating connector of an output connector which in turn is connected with an electronic device. Accordingly, the conductors of the flexible circuits do not require termination by a separate fanout board, such that the cable is essentially ready for use with the flexible circuits in an as-manufactured condition.
From the above, it can be appreciated that the high-density cable of this invention does not require an assembly and termination process as intensive as conventional coaxial cables, and can be produced by automated processes at a lower cost than coaxial cables without any loss in transmission capability. More particularly, the cable does not require termination with a separate fanout board, but instead is equipped with connection regions that are integrally formed with the flexible substrates that carry the conductors necessary for signal transmission. The flexible circuits thus formed can then be arranged and encased in the flexible sheath. To facilitate the assembly process, individual conductors of each flexible circuit can be coded or otherwise identified to ensure that the flexible circuits are properly arranged in the stack within the cable. The cable is then ready for connection to the desired electronic devices, with each connection region of the cable being directly coupled with a connector of one of the electronic devices.
Other advantages of this invention will be better appreciated from the following detailed description.